1. Field of the Invention
The present invention relates to a hoop material cutter which is installed on an automatic press machine or the like to cut a scrap hoop material, and, more particularly, to a cutting blade guide for guiding the movable blade of a hoop material cutter in a reciprocating motion.
2. Description of the Related Art
This type of hoop material cutter is known and disclosed in, for example, U.S. Pat. No. 4,664,007. In this hoop material cutter, as shown in FIG. 11, as a cam 10 secured via a key 9 to the shaft 8 of a motor 6 rotates, a ram 4 moves reciprocally via a bearing 19, while rocking, so that a hoop material is cut between a movable blade 3 attached to the bottom side of the ram 4 and a fixed blade 2 secured to the base plate.
Some schemes of guiding the end faces of the movable blade in reciprocation in this hoop material cutter are taught in, for example, Japanese Unexamined Patent Publication No. Hei 7-60531 and Japanese Unexamined Patent Publication No. Hei 7-60532.
According to the invention disclosed in Japanese Unexamined Patent Publication No. Hei 7-60531, as apparent from a plan view of the ram 4 in FIG. 12, both end faces of the movable blade 3 secured to the front portion of the bottom side of the ram 4 are guided by a pair of guide pins 54 which are rotatably provided on a base plate 1. In this structure, the width of the ram 4 is designed smaller than the width of an opening 63 of the base plate 1, and an oil can manually be supplied to the guide pins 54 from the outer surface of the base plate 1 via nipples 62 and oil holes 61.
According to the invention disclosed in Japanese Unexamined Patent Publication No. Hei 7-60532, as shown in FIG. 13, the ram 4 in FIG. 11 is designed in such a way that the distance between two parallel sides 4a and 4b is set greater than the width of an opening portion 1a, 1b of the base plate 1 and the wide parallel portion is provided on the slide surface of the base plate 1, thereby ensuring more stable reciprocation of the ram 4. Further, cutting blade guides 28a and 28b are provided between end faces 3a and 3b of the movable blade 3 secured to the front end portion of the bottom side of the ram 4 and the inner walls of the opening portion 1a, 1b of the base plate 1. The cutting blade guides 28a and 28b are so designed as to fit guide pins 11a and 11b in a rotatable manner in respective prismatic blocks 29a and 29b, which are fitted detachable in a horizontal direction from the base plate 1, and to cause the cylindrical surfaces of the guide pins 11a and 11b to protrude sideways from the associated blocks, whereby the end faces 3a and 3b of the movable blade 3 are guided by the protruding portions.
The aforementioned conventional hoop material cutter is provided with a hopper 30 which guides a hoop material A between the movable blade 3 and the fixed blade 2 at the time of cutting the hoop material A.
As shown in FIG. 11, the hopper 30 comprises a lower guide 31 for guiding the bottom side of a hoop material A1 and a stock guide 32 provided upright for stopping feeding of a hoop material A2.
As mentioned above, the guide pins 54 of the hoop material cutter described in Japanese Unexamined Patent Publication No. Hei 7-60531 are so designed as to permit manual supply of an oil to the guide pins 54 via the nipples 62 from outside the base plate 1. When a user forgets oil supply to the guide pins 54, for example, and the oil runs out, however, the guide pins 54 will not rotate smoothly, accelerating the wear-out of the cylindrical surfaces, which is likely to cause settling of the guide pins 54. In addition, the attachment of the nipples 62 undesirably makes the side surfaces of the base plate 1 weaker.
The hoop material cutter described in Japanese Unexamined Patent Publication No. Hei 7-60532, as shown in FIG. 13, is constructed in such a manner that the lubricating fluid is supplied to the slide surfaces of the wide parallel portion 4a, 4b of the ram 4 via oil holes 15, a groove 23, a through hole 17 and a groove 24 from nipples 16 in FIG. 11. Although the fluid is further led to the guide pins 11a and 11b via the slide surfaces, it is difficult to sufficiently supply the fluid there. As a result, the guide pins 11a and 11b will not rotate smoothly, so that the cylindrical surfaces of the guide pins 11a and 11b are apt to wear out. As the cylindrical surfaces of the guide pins 11a and 11b wear out, therefore, settling occurs at the end portions of the guide pins 11a and 11b. This settling imparts the rotational resistance that makes the rotation of the guide pins harder and harder.
The conventional hoop material cutter has not sufficiently overcome the adverse influence of the attachment position of the hopper 30 on the action of cutting the hoop material A. For example, when the lower guide 31 is improperly positioned at the cutting time in FIG. 14, the hoop material A1 abuts on the lower end portion of the lower guide 31 and is bent. Consequently, not only a cut chip A3 is deformed, but also the lifetime of the cutting blade becomes shorter due to the poor cutting condition. If the stock guide 32 is positioned improperly, chips or debris 38 may come onto the slide surfaces from the top surface of the movable blade 3, adversely affecting the action of the ram 4.
Accordingly, it is an object of the present invention to provide cutting blade guides for a hoop material cutter, which ensure the smooth rotation of guide pins for guiding a movable blade and facilitate the maintenance of the guide pins.
It is another object of this invention to provide a hoop material cutter capable of smoothly guiding a hoop material between a fixed blade and a movable blade for adequate cutting of the hoop material and also cutting the hoop material without affecting the action of the movable blade.
To achieve the objects, according to one aspect of this invention, a hoop material cutter for cutting a hoop material comprises a base plate; a ram movable reciprocally while rocking; a movable blade secured to a bottom surface of the ram; a fixed blade secured to a top surface of the base plate; a hopper for guiding a hoop material between the movable blade and the fixed blade; and cylindrical guide pins rotatably fitted in the base plate and each having both ends chamfered, cylindrical surfaces of the guide pins having projections protruding sideways of the base plate for guiding end faces of the movable blade, whereby the hoop material cutter cuts the hoop material while allowing the movable blade to move toward and away from the fixed blade in accordance with an action of the ram.
As both ends of each guide pin are chamfered, the chamfered portions become an oil retainer to ensure sufficient oil supply, and if the cylindrical surfaces of the guide pins wear out, causing settling, the settling is accommodated in the space that is formed by the chamfered portions, thus preventing the guide pins from rotating unsmoothly.
According to another aspect of this invention, a hoop material cutter for cutting a hoop material comprises a base plate; a ram movable reciprocally while rocking; a movable blade secured to a bottom surface of the ram; a fixed blade secured to a top surface of the base plate; a hopper for guiding a hoop material between the movable blade and the fixed blade; and cylindrical guide pins rotatably fitted in the base plate via blocks and each having both ends chamfered, cylindrical surfaces of the guide pins having projections protruding sideways of the blocks for guiding end faces of the movable blade, whereby the hoop material cutter cuts the hoop material while allowing the movable blade to move toward and away from the fixed blade in accordance with an action of the ram.
As both ends of each guide pin are chamfered, the chamfered portions become an oil retainer to ensure sufficient oil supply, and if the cylindrical surfaces of the guide pins wear out, causing settling, the settling is accommodated in the space that is formed by the chamfered portions, thus preventing the guide pins from rotating unsmoothly. Further, as the guide pins are fitted in the base plate via the associated blocks, even when the distances between the end faces of the movable blade and the associated guide pins become longer as in a large hoop material cutter, the extension of the guide pins by the blocks can ensure the guiding action.
According to a modification of the first or second aspect, the amount of the cylindrical surface of each of the guide pins protruding sideways of the base plate or the associated block is smaller than the radius of that guide pin.
As the portion of the cylindrical surface of each guide pin which is greater than its radius is fitted, the guide pin can be held in the fitting hole and can be prevented from coming off the fitting hole in the horizontal direction.
According to another modification, the blocks are provided detachable in a horizontal direction from the base plate facing the end faces of the movable blade.
With this structure, the blocks are located on the base plate side facing the movable blade and are attachable and detachable in the horizontal direction, so that the blocks can be pulled out from the base plate simply by removing the movable blade from the bottom surface of the ram.
According to the third aspect of this invention, a hoop material cutter for cutting a hoop material comprises a base plate; a ram movable reciprocally while rocking; a movable blade secured to a bottom surface of the ram; a fixed blade secured to a top surface of the base plate; and a hopper for guiding a hoop material between the movable blade and the fixed blade, the hopper including a lower guide and a stock guide for stopping feeding of the hoop material, a lower end portion of one of the lower guide and the stock guide abutting on an upper surface of the movable blade in a slidable manner, an end portion of the other one of the lower guide and the stock guide being set approximately at a position of a cutting blade on an upper surface of the fixed blade, whereby the hoop material cutter cuts the hoop material while allowing the movable blade to move toward and away from the fixed blade in accordance with an action of the ram.
With this structure, the lower end portion of one of the lower guide and stock guide of the hopper abuts on the top surface of the movable blade in a slidable manner, eliminating a clearance therebetween, which prevents chips or debris 38 from coming onto the slide surfaces. Further, the end portion of the other one of the lower guide and the stock guide is secured at a position where it does not stick out on the movable blade side from the position of the cutting blade of the fixed blade. This design can prevent a hoop material from being deformed at the time the hoop material is cut, and can elongate the lifetime of the cutting blade.
According to a modification of the third aspect, the width of an opening defined by the lower end portion of the lower guide or the stock guide and a blade edge of the fixed blade is set approximately twice the thickness of a hoop material.
As the width of the opening is set approximately twice the thickness of a hoop material, it is possible to cope with deformation of the hoop material or a change in the thickness of the hoop material.
According to a further modification of the third aspect, a side guide for guiding a hoop material in a widthwise direction thereof is provided on both sides of the opening, and the length of the side guide along the opening is set within the length of the cutting blade.
As the side guide is provided to guide the widthwise movement of a hoop material is guided within the width of the cutting blade, the hoop material can be prevented from having any residual stock removal.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.